Concrete slab forming machine with high extrusion capacity

ABSTRACT

During a ram stroke, a ram plate forces a concrete mix from a ram chamber into a slab forming cavity and a gate member closes to isolate the ram chamber from a supply hopper. The supply hopper includes a rotary feeder having a hypocycloid cross section for transporting the concrete mix through the hopper to the ram chamber.

United States I Patent 1191 Kalns [4 July 30, 1974 CONCRETE SLAB FORMING MACHINE 2,388,805 1-1/1945 5mm... 222/409 x WIT HIGH EXTRUSION CAPACITY 3,143,782 8/1064 Kalns 425/218 [76] Inventor: Arvlds Kalns, 541 Central Ave., FOREIGN PATENTS OR APPLICATIONS I Albany, N.Y. 12206 543,479 10/1955 ltaly 425/209 [22] Flled: 1973 Primary Examiner-Allen N. Knowles [21] App]. No: 327,209 Assistant Examiner-David A. Scherbel Attorney, Agent, or Firm-Bruns & Jenney 52 US. Cl 222 235 222 346, 42 2 9, 1 I I 4 13 [57] ABSTRACT [51] Int. Cl. G01f 11/02 During a ram stro flfl a plate o ces a onc [58] Field of Search 222/234, 235, 345, 346, mix from a ram chamber into a slab forming cavity 222/409, 372; 417/209, 218, 59, 447; and a gate member closes to isolate the ram chamber 425/209, 447 from a supply hopper. The supply hopper includes a rotary feeder having a hypocycloid cross section for [56] References Cited transporting the concrete mix through the hopper to UNITED STATES PATENTS the ram chamber- 2,095.509 10/1937 Merchen 222/409 X 2 Claims, 2 Drawing Figures O v A PATENTEDJuLsomu SHEET 10F 2 BACKGROUND OF THE INVENTION This invention relates to the extrusion of concrete, and more particularly to apparatus for efficiently extruding concrete slabs.

A concrete slab produced by the apparatus of the invention and used for the construction of walls and floors of buildings normally has a minimum thickness of six inches and has therethrough a plurality of evenly spaced cylindrical holes with axes parallel to the faces of the slab. Providing the holes reduces the weight and material cost of the slab.

As is known to those skilled in the art, concrete has a high compression strength and a low tensile strength. Typically, embedded within the slab are steel rods aligned in a direction parallel to the axes of the holes whereby the tensile strength of the slab is increased. Additionally, the rods may be kept in tension while the concrete of the slab solidifies, whereby the slab is in compression when the tension is removed. The compression further increases the tensile strength of the slab.

The slabs described hereinbefore are produced by either wet casting or extrusion. In wet casting, a wet concrete mix is placed in a mold containing the steel rods and forms for forming the cylindrical holes; when the concrete solidifies, the forms are removed.

Extruding the slabs is more economical than wet casting because forms are eliminated and labor cost reduced. Thus, an almost dry concrete mix is used in an extrusion machine which extrudes an almost solidified slab. A concrete extrusion machine disclosed by Kalns in US. Pat. No. 3,143,782 typically provides extruded slabs of about 4 feet wide and of any desired length. In the commercial application of the Kalns machine the extruded slab can have any desired length and can be cut by a cutting machine to provide slabs of the length required for construction.

The Kalns machine is comprised of a supply hopper through which the concrete mix is fed onto a floor surface in a ram chamber between a ram plate and the inlet of a forming cavity enclosed by a pair of side members, a floor surface and a top member. The ram plate is coupled to a hydraulic actuator which provides a force for forcing the plate towards the inlet (referred to as a ram stroke, hereinafter), thereby forcing the concrete mix into the forming cavity and forcing extruded concrete from the distal end thereof upon the floor surface. The machine moves on rails away from the extruded concrete at the speed of the extrusion thereby forming a slab extending along the path of the machine, between the rails. The cylindrical holes referred to hereinbefore are provided by a plurality of cylindrical mandrels within the forming cavity extending from the inlet to the distal end. The steel rods may be embedded by the alignment thereof between the rails prior to the extrusion.

In the Kalns machine, the ratio of the length of an extrusion, in response to a ram stroke, to the length of the ram stroke (about 0.4-0.5) is a measure of the stroke efficiency of the machine. The stroke efficiency is'related to the rate at which the machine extrudes concrete (extrusion capacity). It has been found that the extrusion capacity of the Kalns machine can be improved by increasing the stroke efficiency, increasing the quantity of the concrete mix fed into the ram chamber and increasing the number of ram strokes provided during a fixed period of time.

Since continuing commercial successof concrete extrusion machines is related to their capacity, a need exists for machines having a higher capacity than heretofore known in the art.

SUMMARY OF THE INVENTION The principal object of the present invention is to provide improved Kalns machines which have a high extrusion capacity.

According to the present invention, in a machine of the type disclosed by Kalns, a gate is positioned between the supply hopper and the ram chamber during each ram stroke of the machine.

In further accord with the present invention, a rotary feeder having a generally hypocycloid cross section is rotatably mounted between side walls of the supply hopper of a machine of the type disclosed by Kalns.

The present invention provides improved Kalns machines where the discharge hopper is isolated from the ram chamber during at least a portion of the ram stroke thereby increasing the stroke efficiency of the machine. An improved feeder in the discharge hopper increases the rate at which a concrete mix can be fed into the ram chamber of the machine.

Other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of a preferred embodiment thereof as illustrated in the accompanying drawmg.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation, partly in section, of the preferred embodiment of the present invention; and

FIG. 2 is a sectional view along the line 2-2 of FIG. 2 looking in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, the improved Kalns machine of the invention is comprised of a supply hopper 10 open at its upper end 12 and having an outlet port 14 in its lower end. The hopper 10 includes a support section 16 which is fixedly mounted upon a top plate 18. In the disposition of the hopper 10, the output port 14 is disposed above a ram chamber 20 and in the preferred embodiment, a cement mix is fed into the ram chamber from the hopper 10 via the outlet port 14.

At predetermined time intervals, a vertical ram plate 21 is moved through the chamber 20 towards the inlet end of a slab forming cavity 22 which is enclosed by a floor surface 23, the top plate 18 and side plates 24 of the machine. The cement mix in the chamber 20 is thereby forced into the cavity 22 by a ram stroke of the ram plate 21. The dash lines 22a indicate the approximate position of the ram plate 21 at an intermediate point of its stroke. The cement mix forced into the inlet end of the cavity 22 forces extruded concrete from the distal end thereof (not shown). After the ram stroke, the ram plate 21 is retracted back through the chamber 20, more concrete mix is fed from the hopper 10 and the ram stroke is repeated.

A. horizontal ram plate leg 26, integral with the ram plate 21, is connected to the piston of a hydraulic ram plate actuator (not shown). In response tohydraulic fluid being admitted into the extrusion end of the actuator, ram plate 21 is moved toward the cavity 22' thereby providing a ram stroke. In response to fluid being admitted into the retraction end of the actuator, the ram plate 21 is retracted. Y

In the present invention, during a ram stroke a closure gate member 28 having an arcuate blade 30 isolates the chamber 20 from the hopper 10. The blade 30 prevents any portion of the concrete mix in chamber 20 from being forced back into the hopper by ram plate 21.

The arcuate blade 30 of gate member 28 extends at a right angle from the lower end of an external operating arm 32 having the general shape of a bell crank, the blade extending into the hopper through a slot 31. Blade 30 is positioned in the hopper 10 for pivotal movement about the axis of curvature of the blade. To this end, the member is rotatably mounted on an axle 34 by means of a bearing 36, FIG. 2. A coupling pin 38 extends outwardly from the upper end of the arm 32, and this pin is connected to the piston rod 40 of a hydraulic gateactuator 42, FIG. 1.

The gate actuator 42 hashydraulic lines 46, 48 connected thereto. In response to fluid being admitted to the actuator through line 46, the actuator piston causes rod 40 to move in the direction indicated by arrow 49 whereby blade 30 substantially closes the port 14. In response to fluid entering the gate actuator 42 through the line 48, the rod 40 moves in the opposite direction whereby the arm 32 and blade 30-move to open the port 14. The lines 46, 48 are connected to admit hydraulic fluid simultaneously with the respective admissions of fluid to the extrusion and retraction ends of the ram plate actuator. Therefore, the blade 30 only closes the port 14 during a ram stroke.

In the preferred embodiment, the stroke efficiency of the Kalns machine is substantially increased when the port 14 is either closed or partially closed during a ram stroke. At the very beginning of the ram stroke, the leading edge 50 of the blade 30 may move, for example, to a point 52; at the end of the ram stroke, the edge 50 may move to a point 53. When the blade 30 only moves to point 52, the hopper 10 is isolated from the chamber towards the end of the ram stroke. The concrete mix in the chamber 20 at the beginning of the ram stroke is compressed at the end of the ram stroke within a reduced volume between the ram plate 22 and the cavity 24. Accordingly, during the end of the ram stroke some of the concrete mix may be pushed towards the hopper 10, against the blade which prevents the concrete mix from being forced back into the hopper 10. Therefore, isolation of the hopper 10 from the chamber 20 towards the end of the ram stroke increases the stroke efficiency more than isolation at the beginning of the ram stroke.

Within the hopper 10, a rotary feeder 54 having a generally hypocycloid cross section is fixedly mounted upon the axle 34. The concrete mix is provided through the upper end 12 to troughs between the cusps of the feeder 54. In response to rotation of the axle 34, the concrete mix is fed through the outlet port 14 into the chamber 20. The feeder 54 provides feed of the concrete mix to thechamber 20 during the feed cycle.

One end 56 (FIG. 2) of the axle 34 is journalled in a bearing 58 in an upstanding member 60 supported by a side plate 62. The end 56 may be connected to any suitable source of rotary power to rotate the feeder 54.

Referring again to FlG. l, a knife edge 62 may be provided to scrape concrete mix from the leg 26 during the ram stroke and the retraction, thereby substantially preventing a buildup of cement on the leg 26.

A mandrel64 is supported within the cavity 22 by a support arm 66. A plurality of mandrels and support arms are typically included within the Kalns machine for providing holes along the length of an extruded slab as disclosed in US. Pat. No. 3,l43,782.

Thus there has been shown an improved Kalns machine wherein the supply hopper 10 is isolated from the ram chamber 20 during the ram stroke and a rotary feeder 54 provides the concrete mix through the hopper 10 during the feed cycle. Accordingly, the improved machine has a higher extrusion capacity than machines heretofore known in the prior art.

Although the invention has been shown and described with respect to a preferred embodiment thereof, it should be understood by those skilled in the art that various changes and omissions in the form and detail thereof may be made therein without departing from the spirit and the scope of the invention.

I claim:

1. In a concrete extrusion machine of the type in which a concrete mix is fed from a hopper by a feeder mounted on an axle in the hopper to a ram chamber during the retraction of a ram plate, the ram plate being moved during a ram stroke from its retracted position through the chamber to force at least a portion of the concrete mix into an extrusion cavity, the hopper communicating with the ram chamber through an opening therebetween, the improvement comprising: a movable closure member for said opening, the closure member including a blade disposed within the hopper for swingable movement therein and an operating arm pivotally supported by said axle, the blade being secured at one end to the operating arm, and means responsive to a ram stroke to pivot the operating arm so that the blade at least partially closes the opening during a portion of the ram stroke.

2. A machine as defined in claim 1 wherein said hopper mounted feeder has a generally hypocycloid cross section. 

1. In a concrete extrusioN machine of the type in which a concrete mix is fed from a hopper by a feeder mounted on an axle in the hopper to a ram chamber during the retraction of a ram plate, the ram plate being moved during a ram stroke from its retracted position through the chamber to force at least a portion of the concrete mix into an extrusion cavity, the hopper communicating with the ram chamber through an opening therebetween, the improvement comprising: a movable closure member for said opening, the closure member including a blade disposed within the hopper for swingable movement therein and an operating arm pivotally supported by said axle, the blade being secured at one end to the operating arm, and means responsive to a ram stroke to pivot the operating arm so that the blade at least partially closes the opening during a portion of the ram stroke.
 2. A machine as defined in claim 1 wherein said hopper mounted feeder has a generally hypocycloid cross section. 